Interlocking device for plural circuit breaker assembly

ABSTRACT

A fast transfer electrical switching mechanism for manually switching a large electrical load between a standard power source and an emergency power source without the standard and emergency power sources being simultaneously connected to the load and within a short time interval which will not cause stoppage of or interference with normal load operation. A housing supports a pair of commercially available molded case electric circuit breakers mounted in side-by-side relationship, one breaker arranged for connection between load and standard power source and the second between load and emergency power source, the breakers being characterized in that the off-on control handle of each breaker must be swung through a larger section of its arc to open the spring loaded electrodes of the breaker than to close them. Each breaker is coupled to an interlocking device which prevents electrical contact between the electrodes of one breaker if the electrodes of the second breaker are closed. A handle assembly, rotatable by an operator and mechanically coupled to the breaker handles permits the operator to simultaneously swing the handles of both breakers, placing the handle of the open breaker in an on position where its electrodes are spring loaded to close but are prevented from closing by the interlocking device until further manual rotation of the handle assembly opens the closed breaker and releases the interlocking device.

United States Patent [1 1' Whitchurch 51 Oct. 23, 1973 INTERLOCKING DEVICE FOR PLURAL CIRCUIT BREAKER ASSEMBLY [76] Inventor: Norton W. Whitchurch, 2871 Rice Creek Rd., New Brighton, Minn.

[22] Filed: May 22, 1972 [21] Appl. No.2 255,433

[52] U.S. Cl. 200/50 C, 200/18 [51] Int. Cl. H0l1h 9/26 [58] Field of Search 200/18, 50 C [56] References Cited UNITED STATES PATENTS 1,535,873 4/1925 Stevens 200/50 C 2,349,616 5/1944 Ellis et a1. 200/50 C X 3,303,300 2/1967 Turnbull 200/50 C 3,391,257 7/1968 Frank 200/50 C X Primary Examiner-J. R. Scott Attorney-George F. Williamson et al.

[57] ABSTRACT A fast transfer electrical switching mechanism for manually switching a large electrical load between a standard power source and an emergency power source without the standard and emergency power sources being simultaneously connected to the load and within a short time interval which will not cause stoppage of or interference with normal load operation. A housing supports a pair of commercially available molded case electric circuit breakers mounted in side-by-side relationship, one breaker arranged for connection between load and standard power source and the second between load and emergency power source, the breakers being characterized in that the off-on control handle of each breaker must be swung through a larger section of its arc to open the spring loaded electrodes of the breaker than to close them. Each breaker is coupled to an interlocking device which prevents electrical contact between the electrodes of one breaker if the electrodes of the second breaker are closed. A handle assembly, rotatable by an operator and mechanically coupled to the breaker handles permits the operator to simultaneously swing the handles of both breakers, placing the handle of the open breaker in an on position where its electrodes are spring loaded to close but are prevented from closing by the interlocking device until further manual rotation of the handle assembly opens the closed breaker and releases the interlocking device.

9 Claims, 7 Drawing Figures PAIENIEDncI 23 ms sum 1 [IF 2 mun-10mm: 3767372 SHEET 2 0F 2 ...4 (II/IA NORMAL EMEEGE/VCV rt pa able ma eto the m u e sprqsram motors. Where large numbers of motors are used over a large factory area, such a restarting operation can be very time consuming and expensive. Any interruption of power to an operating computer can cause The increasing importance of uninterrupted electrical power, the threat of power outages, and the growing frequency of brownouts due to increasing demand for electricity have prompted many businesses to install emergency power generation equipment for use in the event of interruption of normal electrical power service. Emergency power equipment is kept running continually so it can be immediately substituted for the normal power source in case of outage. The emergency equipment often includes automatic switching equipment, responsive to changes in normal power, to switch automatically to the emergency power system within a few milliseconds when an undesirable change in the normal power source occurs. If equipment such as motors of computers are to be maintained in continuous uninterrupted operation, the transfer from normal to emergency power must occur within approximately 20 milliseconds. A longer period will cause motors to stop operation and may irreparably damage costly computer programs.

To maintain the emergency power system in a continual state of readiness, it must be periodically tested by an operator manually switching the load'from the normal power source to emergency power. The manual switching apparatus used for such testing must be constructed to prevent the load being simultaneously connected to both emergency and normal power sources sincemajor damage to the electrical systems would result from such connection. In addition the manually actuated switching mechanism should connect'the emergency power system to the load within approximately milliseconds after disconnection of the normal power source if there is to be no interference with load operation.

Typically, normal power is supplied by a power company and delivered to the load through a standard molded case electrical circuit breaker having a current capacity of 400 or more amperes. The emergency power source is connected to the load through a second identical circuit breaker, and naturally, only one of the circuit breakers will be closed at any given time.

To prevent both circuit breakers from being simultaneously connected to the load, various interlocking devices may be coupled to the breakers and utilized to insure that only one breaker can be closed at any given time. Accordingly, in present systems when the normal power source breaker is closed, to transfer to emergency power an operator must swing the handle of the emergency power source breaker from off to'- on position. Even with the emergency power breaker handle in on.position the described interlocking device prevents the emergency power breakers electrodes from closing since the normal power breaker is closed. Consequently the emergency power breaker handle will not stay in an on position unless laboreously held in such position by the operator. As is known to one skilled in the art, a 400 ampere breaker or larger breaker is a heavy, cumbersome apparatus requiring substantial force to be applied by the operator to move its handle from an off to an on position, or vice versa or to retain the handle in an on position if the breakers electrodes are prevented from closing by the interlocking device. Accordingly, an operator must presently use one hand to exert the large force to hold the emergency power breaker handle in the on position while simultaneously swinging the handle of the normal power breaker from the on position to the off position. As the normal power breakers electrodes open, the interlocking device permits the electrodes of the emergency power breaker to close, provided that the emergency breaker handle was retained in the on position at the instant the normal breaker opened. Due to the large forces that must be simultaneously applied, operators have frequently experienced difficulty in simultaneously operating the two breaker handles. If for any reason, the operator is unable to retain the emergency breaker handle in an on position at the moment the normal power breaker opens, the load will be without power during the time interval it takes the operator to swing the emergency power breaker handle to on position. If a time lapse of as little as 20-25 milliseconds occurs before the emergency power is connected to the load, the load will be adversely affected to some degree. Naturally the same problems are present when the load is to be switched from emergency power to normal power.

The present invention provides a reliable, easily operated structure by which the operator can switch between emergency and normal power supplies without risk that the time lapse between disconnection and connection will be large enough to damage the load or that simultaneous connection of emergency and normal power sources to load will occur.

SUMMARY OF THE INVENTION The invention comprises an electrical switching mechanism with a pair of commercially available molded case circuit breakers equipped with an interlocking device, the breakers and interlocking device being mounted to a housing and arranged to cooperate with actuation means mounted adjacent the breakers for manually, simultaneously swinging the handles of the breakers in a desired manner described hereafter.

Commercially available molded case circuit breakers embody a sophisticated, spring loaded mechanical system to open and close the electrodes of the breaker when the breaker handle is manually swung through an arc between off and on positions. An important characteristic of that mechanical system which is utilized by the present invention is that the breaker handle must be swung through a larger section of arc to open the electrodes of the breaker than is required to close the same electrodes.

The interlocking deivce which forms an element of the present invention assures that only one of the two breakers can be closed at any given time and may be a rigid beam pivotally mounted to the housing for rocking movement about a fulcrum located centrally on the beam. One breaker is positioned adjacent each end of the beam, each end of the beam having an obstructing pin, madeof insulating material,'pivotally mounted to the beam and arranged to move into and out of the interior of the adjacent circuit breaker through 'a bore passing through the breaker case. The bore is positioned on each breakercase to permit the obstructing pin to move into the interior of the breaker case to obstruct the path of the breakers movable electrode, preventing the movable electrode from moving into electrical contact with the breakers fixed electrode when the obstructing pin is locked within the pathof the movable'electrode by means described hereafter. The positioning ofthe beam and the lengths of the obstructing-pins are selected so onlyone obstructing pin can block the path of a movable electrode at any given time. When one obstructing pin is in an obstructing position in the path of a movable electrode, the second pin will be held in a position outside the path of the already closed movable electrode of the remaining breaker but in contact with the movable electrode. The restraint exerted on the obstructing pin by the closed electrode in contact therewith is sufficient to keep the remaining obstructing pin within the path of the movable electrode of the open breaker to prevent the open breaker from closing if the operator inadvertently tries to close the open breaker while the remaining breaker is closed.

The invention has actuation means mounted adjacent the pair of breakers, and includes a platform spaced from the handles of the breakers and on which a slide is pivotally mounted. The platform has a pair of parallel slots positioned directly along the arc followed by the breaker handles as they move between on and off positions. Handle extensions are coupled to the breaker handles and have extending posts which pass through and move freely along the parallel slots of the platform as the handles are swung. The slide is provided with a pair of orifices therethrough which engage the posts of the handle extensions so that pivotal movement of the slide swings the posts in opposite directions along the parallel slots. Swinging of the pivotally mounted slide in a given rotational direction causes one breaker handle to be moved from an on toward an off position and the remaining handle to simultaneously move from an off toward an on position, or vice versa.

Because a breaker handle moving fron an on position to an off position must travel through a larger are before its associated movable electrode opens than is required to close the movable electrode of an already open breaker, the handle of the open breaker will have reached the on position and its associated movable electrode will be spring loaded to snap to a closed position before the closed breaker opens. The open breaker cannot close, however, until the obstructing pin of the interlocking device is withdrawnfrom the path of the breakers still open, spring loaded movable electrode. The pin is withdrawn from the path when the closed breaker opens in response to further movement of the handle of the closed breaker along its arc toward off position. Once the closed breaker opens, the remaining breaker closes within 10-15 milliseconds, assuring that the load is not adversely affected.

The invention provides a sturdy, relatively in expen sive, highlyreliable, long lasting apparatus which is easily manufactured and assembled for transferring a load from a normal power supply to an emergency power supply and vice versa without danger that the load will be connected simultaneously to both power sources or that an undesirable time lag occurs during switching of the systems.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the invention with the electrical circuit breakers shown in phantom.

FIG. 2 is a sectional, side view of the invention.

FIG. 3 is a sectional side view of the interior of a molded case circuit breakerwith the breaker in an open condition.

FIG. 4 is a sectional side view of the interior of a molded case circuit breaker with the breaker in a closed condition.

FIG. 5 is a sectional side view of the interior of a molded casecircuit breaker showing the breakers movable electrode in an open position and prevented from closing by an-obstructing pin of an interlocking device.

FIG. 6 is a front elevational' view of the actuation means of the invention taken along line 6-6 in FIG. 1 showing the handle assembly in alternate positions.

FIG. 7 is a schematic electrical circuit diagram of the invention showing its mode of connection between the load and normal and emergency power sources.

DESCRIPTION AND OPERATION OF THE INVENTION Referring now to FIGS. 1 and 2, the invention 10 is shown in a standard'operating position on an electrical panel housing 11. g

Two commercially available molded case electrical circuit breakers 1 2 and 13 are shown rigidly attached to a supporting framework 14 within the housing 11, the framework in turn supported by rigid box channels 15 and 16 to which the framework 14 is welded. The housing 11 has removable facings l7 and 18, the hinged facing 17 having a rectangular opening 19 through which the breaker handles 22 and 23 of breakers 12 and 13, respectively, project outwardly. Although a specific housing 11 is shown in use with the invention, it should be understood that other housings can as readily be used with or adapted to the invention and are within its purview.

Electrical circuit breakers l2 and 13 are substantially identical, commercially available, molded case circuit breakers having substantial current capacity, inter alia approximately 4 q0 a rnperes or more per breaker. Since each of these breakers plays a substantial role in the invention, the structure and operation of one such breaker will be discussed in further detail. FIGS. 3 -5 show the interior of such breakers in different stages of operation but omit a number of mechanical parts for purposes of simplification.

As is known to those skilled in the art, a molded case electrical circuit breaker 13 (FIG. 3) has a highly sophisticated mechanical system with a plurality of link ages and pivotal mountings joining a movable electrode 33 and the breaker handle 23. Since the particular mechanical linkage is not important to the present invention, such linkages have been simplified or omitted from FIGS. 3 5 to avoid needless complication. The breaker handles 22 and 23 tightly enclose a metal brace 20 rigidly fixed to and extending from a base member 21 to which two pairs of relatively powerful springs, first pair 40 and second pair 41, are secured, each pair of springs connected to opposite ends of a rocking linkage 42 which through additional linkages, omitted for simplification, actuate the movable electrode 33 for movement between open position 43 and closed condition 47.

The relatively powerful spring pairs 40 and 41 assure that the movable electrode 33 remains in an open condition 43 when the breaker handle 23 is in an off position 44 (FIG. 3). When the handle 23 is swung to the on position 45, the rocking linkage 42 pivots in a counterclockwise direction to drive movable electrode 33 toward adjacent fixed electrode 46 retaining it in a closed condition 47 in electrical contact with fixed electrode 46. When handle 23 is moved to an off position 44, the rocking linkage 42 transmits movement through the mechanical system to movable electrode 33 to swing it to the open condition 43.

The breaker 13 has a rigid outer molded casing 48 of insulating material, including a base 49 on which the fixed electrode 46 is rigidly mounted. The movable electrode 33 is pivotally mounted for swinging movement along a path 50 between an open condition 43 (FIG. 3) wherein the breaker electrodes 33 and 46 are spaced apart and a closed condition 47 (FIG. 4) wherein the electrodes 33 and 46 are in electrical contact. It should be understood that although only a single pair of electrodes are shown in FIGS. 3 5, in practice each breaker may have a greater number, commonly three pairs, all of which move simultaneously in response to the breaker handle 23. The position of the movable electrode 33 is controlled by swinging the pivotally mounted breaker handle 23 along an are 51 (FIG. 3) extending between off position 44 and on position 45, the movable electrode 33 ordinarily being in a closed condition 47 (FIG. 4) when the handle 23 is in on position 45 and in an open condition 43 (FIG. 3) when the handle is in an off position 44. Breaker 12 is connected between the electrical load and the normal power source, while breaker 13 is connected between the electrical load and the emergency power source. Since the breakers are identical, they are interchangeable, and breaker 13 could as readily be connected to the normal power source as breaker 12.

An important characteristic of molded case circuit breakers, in so far as the present invention is concerned, is that breaker handle 23 must be swung through a larger section of the are 51 in order to move movable electrode 33 from a closed condition 47 to an open condition 43 than is required to move electrode 33 from an open condition to a closed condition. It has been found that in response to swinging of the breaker handle 23 the movable electrode 33 moves from the open condition 43 to the closed condition 47 well before the breaker handle has traveled all the way to the on position 45. The length of the arc through which'the handle 23 must be swung to close the breaker is notably less than the length of the are through which the handle 23 must be swung to open the breaker. Thus if the breaker handles of a closed breaker and an open breaker are swung in equal increments toward off position and on position, respectively, the open breaker will close before the closed breaker opens.

Referring now to FIGS. 2 5, an interlocking device 58 includes a rigid beam 59 and a pivotal mounting formed by fulcrum 60, the fulcrum attached to framework 14 and having cooperating bores 61 and 62 with fulcrum pin 63 extending therethrough and retained therein by cotter pins. The beam 59 has a bore therethrough at the approximate center thereof so fulcrum pin 63 may be inserted through the beam and fulcrum to pivotally mount the beam relative to the breakers l2 and 13.

Adjacent each end of the beam 59 are sockets 64 and 65 in which obstructing pins 66 and 67 formed of rigid insulating material are pivotally mounted by means of transverse bolts 68 passing through the beam 59 and the obstructing pin, the transverse bolts retained in position by cotter pins.

As will appear from FIGS. 3 5, the platform 14 has holes 69 and 70 bored therethrough and aligned with an opening 71 in the base of each breaker to permit the obstructing pins 66 and 67 to move through the holes 69 and 70 respectively and opening 71 and into the interior of the circuit breakers to selectively obstruct the path 50 of the movable electrode.

When an electrical breaker 13 is open with its movable electrode in the open condition 43 (FIG. 3), the movable electrode 33 is not in contact with the obstructing pin 67. With the shown interlocking device 58, obstructing pins 66 and 67 are of equal length, so obstructing pin 67 (FIG. 3) will extend into the path 50 of movable electrode 33 only if the remaining obstructing pin 66 at the opposite end of beam 59 is forced out of the path of the movable electrode of the remaining breaker as shown in FIG. 4, where the obstructing pin is in a position 72, the spring loaded electrode 33 exerting sufficient force against the obstructing pin to urge it outward from the case interior and prevent return movement of the pin toward the case interior, thus pivoting the beam 59 and moving the remaining obstructing pin 66 within the path 50 of the movable electrode 33 of the open breaker 13 (FIG. 3).

When normal breaker 12 is in a closed condition 47 as shown in FIG. 4, the movable electrode 33 is firmly held against fixed electrode 46 and the obstructing pin, which is in position 72, by the spring forces exerted by spring pairs 40 and 41. As a consequence, the spring loaded, movable electrode 33 restrains the obstructing pin, keeping it in its shown position 72 until the movable electrode 33 is moved to an open condition. This restraint keeps beam 59 in the orientation shown in FIG. 2 while the breaker 12 is closed; in that orientation the beam 59 keeps the remaining obstructing pin 67 in a position 73 projecting into the interior of the remaining breaker 13 (FIGS. 2 and 3) and in the path 50 of movable electrode 33 so that the movable electrode cannot move into electrical contact with fixed electrode 46. With breaker l3 and interlocking device 58 in the positions shown in FIGS. 2 and 3, should the breaker handle 23 be moved from the off'position 44 toward the on position 45, the breaker handle 23 could be retained in the on position only by continual applied force by an operator. While so retained spring pairs 40 and 41 urge movable electrode 33 toward fixed electrode 46 to the spring loaded position 74 shown in FIG. 5, and electrical contact between the electrodes is prevented only by obstructing pin 67 which is in position 73. If the operator relaxes his applied force on handle 23, the spring pairs would return the handle to off position 44 and the movable electrode to open condition 43. Accordingly it is seen that the interlocking device 58 assures that only one breaker can be closed at a given time and prevents or the simultaneous connection of emergency and normal power sources to the electrical load.

The shown interlocking device includes beam 59,.obstructing pins 66 and 67, fulcrum 60, and the associated hardware pivotally mounting the beam to the fulcrum, the pins 66 and 67 to the beam, and the fulcrum to the framework 14. Although a single interlocking device 58 has been shown with the invention, it should be understood that others could as readily have been used and all such alternative interlocking devices as could be used with or adapted to the present invention by one skilled in the art are within the purview of the claimed invention.

Referring again to FIG. 1, a mounting plate 75 is attached adjacent the faces of breakers l2 and 13 by means of screws positioned at the respective corners of the plate. Numerous types of fastening means can be used to attach the plate 75 to the breakers or to the adjacent housing, all such means being within the purview of the invention. The mounting plate 75 is provided with handle openings 76 and 77, which are ofan appropriate size to permit the breaker handles 22 and 23 and their extensions describedhereafter, to pass therethrough, the handles and extensions when passed therethrough freely moving along the openings 76 and 77 between off and on positions. The breakers are arranged relative to one another such that when one breaker 13 is off and the other 12 on, the breaker handles 22 and 23 are nonparallel and at opposite ends of the handle openings 75 and 76 as shown in FIG. 1'.

A platform 78 with integral legs 79v and 80 welded to mounting plate 75 or fixed relative thereto by other means known to the art, has parallel slots 82 and 83 spaced from one another (FIGS. 1 and 6). A central rod 84 (FIG. 2) extends from plate 75 to and through the platform 78, providing a pivotal mounting about v which a handle assembly 85 is mounted.

Handle extensions 52 and 53 slip over and closely surround breaker handles 22 and 23, respectively, each extension being retained on the breaker handle by means of a bolt 54 and nut 55, (FIG. 3) the bolt passing through the extension and the breaker handle. The outermost end of the extensions 52 and 53 are provided with rigid posts 56 and 57, respectively, extending therefrom which serve an important purpose to be described hereafter.

The slots 82 and 83 have stops 86 at each end thereof, the length of each slot being adequate to permit the post of the associated breaker handle extension to move between off and on positions, but not beyond the limits needed for movement to off and on positions. These stops 86 assure that excessive force applied to the handle assembly 85 by an operator are not applied to the breaker handles 22 and 23 and do not thereby damage the mechanical system in the breakers on the handles themselves. The stops 86 prevent movement of the breaker handles beyond the limits needed for operation of the breakers.

The handle assembly 85 has a slide 87 of rigid material and provided with central aperture 88 through which rod 84 passes, the slide being retained on the rod 84 for pivotal movement relative thereto by means of a cotter pin. The handle assembly 85 also includes opcrating handles 89 and 90 extending outwardly from the slide, the handles being ofa length adequate to permit an average operator to easily swing the handle assembly about the rod 84 when coupled to the breaker handles as will be further described hereafter.

The slide 87 has means engaging the posts 56 and 57 of the handle extensions, such as post engaging orifices 91 and 92 (FIGS. I and 6), the orifices being arranged and shaped to remain in communication with the parallel slots 83 and 82, respectively as the slide pivots about rod 84, carrying each orifice between stops 86 of its associated slot. The platform 78, mounting plate 75, handle assembly 85, breaker handle extensions 52 and 53, and means to mount the plate relative to the breakers and to pivotally mount the handle assembly on the platform 78, such as rod 84, collectively comprise one type of actuation means for the breakers l2 and 13. It should be understood that numerous equivalents of the shown actuation means could be fabricated by those skilled in the art, and all such structures are within the purview of the invention.

The posts 56 and 57 of breaker handle extensions 52 and 53 pass through slots 82 and 83, respectivly, of the platform 78 and also through post engaging orifices 91 and 92, respectively, of thehandle assembly. Pivoting movement of the handle assembly about rod 84 moves the posts 56 and 57 in opposite directions along slots 82 and 83 respectively, thereby swinging the breaker handles 22 and 23 and their extensions between off an on positions.

The breakers 12 and 13 are arranged in the housing 11 so their handles 22 and 23 move substantially hori-,

zontally when swung between off and on positions. The actuation means is arranged so that the operating handles 89 and are rotated within a vertical plane with the handles positioned so'that one of the handles must be moved downward to transfer electrical power from one breaker to the other. This arrangement permitting downward movement for all transfers allows an operator to utilize his own weight to actuate the switching mechanism 10.

An outer cover member 93 (FIGS. 1 and 2) provides a protective guard to prevent an operators clothing from becoming entangled in the handle assembly and improves esthetic appearance. The cover member 93 is attached to the platform 78 by screws or other means knownto the art and carries position identification signs 94 and 95 to indicate whether the normal or emergency power source is connected to the load. The load is connected to the power source whose name appears adjacent the handle 89, the normal source being connected in FIG. 1. Accordingly, when the handle 89 is adjacent the emergency sign 95, the normal power source has been disconnected and the load is connected to the emergency powersource- Referring now to. FIGS. 3 and 7, a commercially available microswitch 96 has its actuating lever 97 in physical contact with the mechanical system of the breaker 13, the lever 97 and microswitch 96 being constructed and arranged to close the switch 96 when the breakers movable electrode 33 is in a closed condition 47, and to open the microswitch when the movable electrode 33 is in an open condition 43. The microswitch 96 is connected in series with indicating lamp 98 in indicating lamp circuit 99 powered by standard volt alternating current. When the microswitch 96 closes, the lamp 98 lights to indicate that the normal power breaker 12 is closed. A second indicating lamp normal power breaker 12 is connected between the normal source of electrical power 102 and load 103, and the emergency breaker 13 between the emergency power source 104 and the same electrical load. As is clear to one skilled in the art, the shown electrical system is a three phase power system. Naturally, the principles of the invention are equally applicable to direct current transmission systems.

In operation, the actuation means is mounted adjacent the brcakcrs 12 and 13, one brcakcr handle extension 52 being in an on position and the other extension handle 53 in an off position as shown in FIG. 1 where the normal power breaker 12 is in the on position. Accordingly, with the handle assembly 85 in the position 105 (FIGS. 1 and 6) electrical power flows from the normal power source 102 (FIG. 7) through breaker 12 and thence to the load 103. Since normal power source breaker 12 has its movable electrode 33 in closed condition establishing electrical contact with the fixed electrode 46 (FIG. 4), actuating lever 97 of microswitch 96 closes the switch 96, causing the normal power source indicator lamp 98 (FIGS. 1 and 7) to light in response to current flowing from the 110 volt source 106, through switch 96, and thence to the lamp 98. Since emergency power breaker 13 is open, its corresponding microswitch is in an open condition and emergency power indicator lamp 101 is off.

With normal power breaker l2 closed, its movable electrode 33 is in closed condition 47, establishing electrical contact with fixed electrode 46 as shown in FIG. 4. The spring pairs 40 and 41 hold the movable electrode 33 firmly against the fixed electrode 46 and the obstructing pin is retained thereby at position 72 urging the obstructing pin outward from the breaker interior. This results in the end 107 of beam 59 being urged away from framework 14. With the movable electrode 33 as shown in FIG. 4 the obstructing pin cannot move further into the interior of the breaker, and accordingly the remaining obstructing pin 67 at the oppsite end 108 of the beam 59 (FIG. 2) is moved into the emergency power breaker 13 providing a positive obstruction within the path 50 (FIG. 3) of the movable electrode 33 to prevent the electrode from moving to a closed condition 47 like that shown in FIG. 4. So long as no effort is made to close the emergency breaker 13,

the movable electrode 33 (FIG. 3) does not contact obstructing pin 67.

When it is desired that the load 103 be disconnected from the normal power source 102 and instead connected to the emergnecy power source 104 to test the emergency power source or for other reasons, the operator grasps the operating handles 89 and 90 of the handle assembly 85 and swings the handles in a counterclockwise direction 109 about the central pivot provided by rod 84. As the slide 87 of the handle assembly rotates in response to the operators applied force, the post engaging orifices 91 and 92 urge the posts 57 and 56, respectively, along the parallel slots 83 and 82, respectively in the platform 78. Post 56, associated with the normal power breaker 12 moves in direction 110 as indicated in FIG. 6, while post 57, which is associated with the emergency power breaker 13, moves in the opposite direction 111 along corresponding slot 83. Accordingly, the handle extension 52 of the normal power breaker 12 is swung from an on position toward an off position and the handle of the emergency power breaker 13 from an off position toward an on position.

As indicated earlier, the molded case circuit breakers used with the invention are characterized in that the breaker handle must swing through a larger section of its arc to open a closed breaker than to close an open breaker. As the handle assembly 85 rotates and reaches a position 112 (FIG. 6) the handle extensions 52 and 53 have been urged along their respective arcs in equal increments, carrying the breaker handles 22 and 23 along with them. Accordingly, the handle 23 of the open emergency power breaker 13 has reached a location along its arcwhere its associated movable electrode 33 is spring loaded to close (FIG. 5) but prevented from doing so by the obstructing pin 67 within its path 50. Since the spring loaded, movable electrode 33 of the already closed normal power breaker 12 prevents any movement of its obstructing pin (FIG. 4) in a direction toward the interior of breaker 12, the obstructing pin 67 associated with the emergency breaker 13 is moved into the path 50 of the movable electrode 33 of breaker 13 by pivotally mounted beam 59 which interconnects the pins 66 ahd 67. Because the force exerted by an open movable electrode 33 axially along obstructing pin 67 is less than the axial force exerted on a pin in position 72 by closed electrode 33 (FIG. 4), the open electrode cannot move pin 67 and close the open breaker 13 when the remaining breaker is closed.

' As the operator rotates the handle assemby through the small remaining are required to bring it from position 112 to position 113 (FIG. 6) and thereby swing the breaker handle of the closed normal power breaker 12 to its off position 44, the movable electrode 33 of the normal power breaker moves out of electrical contact with the fixed electrode 46', moving to an open condition 43 (FIG. 3). Simultaneously the strong spring force exerted to close the movable electrode 33 of the emergency power breaker and urging the electrode 33 toward the fixed electrode 46 (FIG. 5) forces obstructing pin 67 outward from the interior of the breaker and retains it in the position 72 shown in FIG. 4, the beam 59 simultaneously pivoting about its fulcrum to move the remaining obstructing pin 66 into the path 50 of the movable electrode of the normal power breaker (FIG. 3) to prevent its closure until the emergency power breaker has been opened. At this stage of operation the interior of the normal power breaker is as shown in FIG. 3 and that of the emergency power breaker as shown in FIG. 4.

When the movable electrode of the normal power breaker opens, actuating lever 97 of microswitch 96 (FIG. 3), is released and the microswitch opens, causing normal indicating lamp 98 (FIG. 1) to turn off. As the emergency breakers movable electrode closes, an identical microswitch associated therewith has its actuating lever urged to a closed position causing the emergency indicator lamp 101 (FIG. 1 and 7) to light, indicating that the emergency breaker is now in operation.

As is known to those skilled in the art, a transfer from one power system to another should be made only when the two systems are substantially in phase. In practice this transfer is accomplished at a timely moment by means ofa synchronizing light which, in effect, measures the phase difference between the two power systems. SUch a light typically glows brightly when the two systems are out of phase and becomes dim when the systems are in phase. Accordingly it is contemplated that such a light, or an equivalent indicating mechanism, should be used with the invention so that the operator will transfer power from one system to the other at the appropriate moment when the systems are substantially in phase..

The invention thus provides a highly reliable, safe, efficient, and easily operated electrical switching mechanism by which a large electrical load can be transferred from one powersystem to another with no danger that the load will be simultaneously connected to both power systems. As is evident from the foregoing description the electrical load is connected to a first power source until a closed electrical breaker opens, and then is reconnected to a second power source within a time lapse defined by the time required for the movable electrode of the second power sources breaker to move from its spring loaded open condition 74 shown in FlG. to its closed condition 47 shown in P16. 4. it has been found that the time lapse required for such movement is typically of the order of l0 milliseconds, a time duration which is small enough that the risk of danger to computerized equipment orthe stoppage of motors or other electrical machinery is negligible.

While the preferred embodiments of the present invention have been described, it should be understood that various changes, adaptations and modifications may be made therein without departing from the spirit of the invention and the scope of the appended claims.

What is claimed is:

l. A fast transfer switching mechanism for manually switching a large electrical load between a'standard power source and an emergency power source without the standard and emergency power sources being simultaneously connected to the load and within a short time interval which will not cause stoppage and interference with load operation comprising:

a housing, including a supporting framework therein;

a pair of electrical circuit breakers positioned adjacent one another and mounted on said framework, each said circuit breaker having a spring loaded movable electrode and an adjacent, fixed electrode, each said movable spring loaded electrode moving along a path into and out of electrical contact with its adjacent fixed electrode in response to swinging of a pivotally mounted breakerhandle along an arc between on and off positions, respectively, each said breaker handle and its said movable electrode mechanically interconnected such that said breaker handle must be swing through a larger section of said are to move said movable electrode out of electrical contact with said adjacent fixed electrode than to move said movable electrode into electrical contact with said adjacent fixed electrode, one of said circuit breakers having terminals for electrical connection between load and standard power source, and the other said circuit breaker having terminals'for connection between load and emergency power source;

an interlocking device within said housing mechanically interconnected with each said circuit breaker, said device mechanically preventing said movable electrode of an open circuit breaker from moving into contacting relationship with its said adjacentv fixed electrode while the remaining circuit breaker has its said movable electrode in electrical contact with its said adjacent fixed electrode, and permitting the said fixed and movable electrodes of said open breaker to achieve electrical contact if said electrodes of theremaining said circuit breaker are not in electrical contact; and

actuation means mounted adjacent said pair of breakers for manually, simultaneously swinging said breaker handles, said means moving one of said breaker handles from off position toward on position and the other said breaker handle from on position toward off position, said breaker, handles being moved simultaneously along their arcs in equal increments to cause said breaker handle of said open breaker to reach its on position before said breaker handle of the closed breaker reaches its off position so said movable electrode of said open breaker becomes spring loaded so as to move into electrical contact with its said adjacent fixed electrode but is prevented from so moving by said interlocking device until said breaker handle of said closed breaker reaches its off position where its said movable electrode opens, causing said interlocking device to permit closing of said spring loaded movable electrode to rapidly achieve electrical contact between said fixed and movable electrodes of said open breaker without danger of both breakers being simultaneously connected to the load.

2. The combination according to claim 1 wherein said interlocking device includes a rigid beam pivotally mounted relative to and between said breakers and fur-' ther includes a pair of obstructing pins pivotally mounted to and extending from said beam, said pair of obstructing pins being made of insulating material; and wherein each said circuit breaker has an opening in its case for receiving one of said obstructing pins for sliding motion therethrough such that one of said obstructing pins moves therethrough into the path of said movable electrode of one of said circuit breakers and the remaining said obstructing pin moves simultaneously out of the path ofsaid movable electrode of said remaining breaker as said beam pivots, said movable electrode of said closed breaker resting against and restraining an obstructing pin to cause said pivotally mounted beam to move said remaining obstructing pin within the path of said open movable electrode to prevent said open movable electrode from moving along its path into electrical contact with its said adjacent fixed electrode while one of said obstructing pins blocks its path, so that only one of said movable electrodes can be in electrical contact with its said adjacent fixed electrode at any given time.

3. The combination according to claim 1 wherein said actuation means includes:

a platform spaced from said breaker handles and fixed relative to said breakers, said platform having a pair of slots therethrough, a slot positioned above and aligned with the arc of each of said breaker I handles;

a pair of breaker handle extensions, one of said extensions attaehed to and extending from each of said breaker handles and each of said extension having a post passing through one of said pair of slots on said platform, each said post moving along its slot in response to movement of said breaker handle between on and off positions; and

' a handle assembly joined to said platform by a pivotal mounting for rotation on said platform, said handle assembly having means engaging said posts of said extensions so that pivoting movement of said handle assembly moves said posts along said slots of said platform, swinging movement of said handle assembly in one direction moving said handle of one of said breakers from an off position toward an on position, and said handle of said second breaker from an on position toward an off position simultaneously.

4. The combination according to claim 3 wherein:

said pair of electrical circuit breakers are positioned relative to each other such that said breaker handles move in parallel arcs;

said slots on said platform are parallel to one another;

and

said handle assembly is constructed and arranged such that swinging movement thereof moves one of said posts of said breaker handle extensions in a first direction along its said slot and the remaining said breaker handle extension post moving in the opposite direction along its said parallel slot.

5. The combination according to claim 3 wherein said platform is mounted to and supported by a base plate fixed relative to said circuit breakers and said plate having openings for said breaker handles to pass therethrough, the pivotal mounting of said handle assembly including a post extending between said base plate and said platform and passing through said platform and said handle assembly, said handle assembly including a pivoting slide, and said means engaging said posts including orifices through said slide for engaging said posts of said handle extensions and moving said the posts along said pair of slots in response to pivoting movement of said slide. 6. The combination according to claim 3 wherein said handle assembly includes a pivoting slide with a pair of handles extending therefrom to permit an operator to grasp said handles to swing said slide about its pivotal mounting.

7. The combination according to claim 6 wherein said circuit breaker handles move substantially horizontally when swung between off and on positions, and said actuation means is positioned so said pair of handles are rotated within a vertical plane with said handle positioned so that one of said handles must be moved downwardly to transfer power between said circuit breakers, thereby permitting an operator to utilize his own weight to actuate the switching mechanism.

8. The combination according to claim 3 wherein said slots have stops at each end thereof positioned relative to said breaker handle extensions to prevent movement of said breaker handle extensions beyond the extremes of the arcs defined by swinging of said breaker handles between off and on positions to prevent application to said circuit breakers of excessive forces applied to said handle assembly.

9. A fast transfer switching mechanism for manually switching a large electrical load between a standard power source and an emergency power source without the standard and emergency power sources being simultaneously connected to the load comprising:

a housing;

a pair of electrical circuit breakers positioned adjacent one another and mounted to said housing, each said circuit breaker having a spring loaded movable electrode and an adjacent, fixed, electrode, each said movable spring loaded electrode moving along a path into and out of electrical contact with its adjacent fixed electrode in response to swinging of a pivotally mounted breaker handle along an arc between on and off positions, respectively, each said breaker handle and its said movable electrode mechanically interconnected such that the breaker handle must be swung through a larger section of said arc to move said movable electrode out of electrical contact with said adjacent fixed electrode than to move said movable electrode into electrical contact with said fixed electrode, one said circuit breaker having terminals for electrical connection between load and standard power source, and the other said breaker having terminals for connection between load and emergency power source;

an interlocking device within said housing mechanically interconnected with each said circuit breaker, said device mechanicallyvpreventing said movable electrode of an open breaker from moving into contacting relationship with its said adjacent fixed electrode while the remaining said breaker has its said movable electrode in electrical contact with its said adjacent fixed electrode, and permitting said fixed and movable electrodes of said open breaker to achieve electrical contact if said electrodes of said remaining breaker are not in electrical contact; and

actuation means for manually, simultaneously swinging said breaker handles along their arcs in equal increments by means of downwardly directed movement of an operator to cause said breaker handle of said open breaker to reach its on position before said handle of the closed breaker reaches its off position so said movable electrode of said open breaker becomes spring loaded so as to move into electrical contact with its said adjacent fixed electrode but is prevented from so moving by said interlocking device until said breaker handle of said closed breaker reaches its off position where its said movable electrode opens, causing said interlocking device to permit closing of said spring loaded movable electrode to achieve electrical contact between said fixed and movable electrode of the open breaker without danger of both said circuit breakers being simultaneously connected to the load. 

1. A fast transfer switching mechanism for manually switching a large electrical load between a standard power source and an emergency power source without the standard and emergency power sources being simultaneously connected to the load and within a short time interval which will not cause stoppage and interference with load operation comprising: a housing, including a supporting framework therein; a pair of electrical circuit breakers positioned adjacent one another and mounted on said framework, each said circuit breaker having a spring loaded movable electrode and an adjacent, fixed electrode, each said movable spring loaded electrode moving along a path into and out of electrical contact with its adjacent fixed electrode in response to swinging of a pivotally mounted breaker handle along an arc between on and off positions, respectively, each said breaker handle and its said movable electrode mechanically interconnected such that said breaker handle must be swung through a larger section of said arc to move said movable electrode out of electrical contact with said adjacent fixed electrode than to move said movable electrode into electrical contact with said adjacent fixed electrode, one of said circuit breakers having terminals for electrical connection between load and standard power source, and the other said circuit breaker having terminals for connection between load and emergency power source; an interlocking device within said housing mechanically interconnected with each said circuit breaker, said device mechanically preventing said movable electrode of an open circuit breaker from moving into contacting relationship with its said adjacent fixed electrode while the remaining circuit breaker has its said movable electrode in electrical contact with its said adjacent fixed electrode, and permitting the said fixed and movable electrodes of said open breaker to achieve electrical contact if said electrodes of the remaining said circuit breaker are not in electrical contact; and actuation means mounted adjacent said pair of breakers for manually, simultaneously swinging said breaker handles, said means moving one of said breaker handles from off position toward on position and the other said breaker handle from on position toward off position, said breaker, handLes being moved simultaneously along their arcs in equal increments to cause said breaker handle of said open breaker to reach its on position before said breaker handle of the closed breaker reaches its off position so said movable electrode of said open breaker becomes spring loaded so as to move into electrical contact with its said adjacent fixed electrode but is prevented from so moving by said interlocking device until said breaker handle of said closed breaker reaches its off position where its said movable electrode opens, causing said interlocking device to permit closing of said spring loaded movable electrode to rapidly achieve electrical contact between said fixed and movable electrodes of said open breaker without danger of both breakers being simultaneously connected to the load.
 2. The combination according to claim 1 wherein said interlocking device includes a rigid beam pivotally mounted relative to and between said breakers and further includes a pair of obstructing pins pivotally mounted to and extending from said beam, said pair of obstructing pins being made of insulating material; and wherein each said circuit breaker has an opening in its case for receiving one of said obstructing pins for sliding motion therethrough such that one of said obstructing pins moves therethrough into the path of said movable electrode of one of said circuit breakers and the remaining said obstructing pin moves simultaneously out of the path of said movable electrode of said remaining breaker as said beam pivots, said movable electrode of said closed breaker resting against and restraining an obstructing pin to cause said pivotally mounted beam to move said remaining obstructing pin within the path of said open movable electrode to prevent said open movable electrode from moving along its path into electrical contact with its said adjacent fixed electrode while one of said obstructing pins blocks its path, so that only one of said movable electrodes can be in electrical contact with its said adjacent fixed electrode at any given time.
 3. The combination according to claim 1 wherein said actuation means includes: a platform spaced from said breaker handles and fixed relative to said breakers, said platform having a pair of slots therethrough, a slot positioned above and aligned with the arc of each of said breaker handles; a pair of breaker handle extensions, one of said extensions attached to and extending from each of said breaker handles and each of said extension having a post passing through one of said pair of slots on said platform, each said post moving along its slot in response to movement of said breaker handle between on and off positions; and a handle assembly joined to said platform by a pivotal mounting for rotation on said platform, said handle assembly having means engaging said posts of said extensions so that pivoting movement of said handle assembly moves said posts along said slots of said platform, swinging movement of said handle assembly in one direction moving said handle of one of said breakers from an off position toward an on position, and said handle of said second breaker from an on position toward an off position simultaneously.
 4. The combination according to claim 3 wherein: said pair of electrical circuit breakers are positioned relative to each other such that said breaker handles move in parallel arcs; said slots on said platform are parallel to one another; and said handle assembly is constructed and arranged such that swinging movement thereof moves one of said posts of said breaker handle extensions in a first direction along its said slot and the remaining said breaker handle extension post moving in the opposite direction along its said parallel slot.
 5. The combination according to claim 3 wherein said platform is mounted to and supported by a base plate fixed relative to said circuit breakers and said plate having openings for said breaker handles to pass therethrough, the pivotal mounting of sAid handle assembly including a post extending between said base plate and said platform and passing through said platform and said handle assembly, said handle assembly including a pivoting slide, and said means engaging said posts including orifices through said slide for engaging said posts of said handle extensions and moving said the posts along said pair of slots in response to pivoting movement of said slide.
 6. The combination according to claim 3 wherein said handle assembly includes a pivoting slide with a pair of handles extending therefrom to permit an operator to grasp said handles to swing said slide about its pivotal mounting.
 7. The combination according to claim 6 wherein said circuit breaker handles move substantially horizontally when swung between off and on positions, and said actuation means is positioned so said pair of handles are rotated within a vertical plane with said handle positioned so that one of said handles must be moved downwardly to transfer power between said circuit breakers, thereby permitting an operator to utilize his own weight to actuate the switching mechanism.
 8. The combination according to claim 3 wherein said slots have stops at each end thereof positioned relative to said breaker handle extensions to prevent movement of said breaker handle extensions beyond the extremes of the arcs defined by swinging of said breaker handles between off and on positions to prevent application to said circuit breakers of excessive forces applied to said handle assembly.
 9. A fast transfer switching mechanism for manually switching a large electrical load between a standard power source and an emergency power source without the standard and emergency power sources being simultaneously connected to the load comprising: a housing; a pair of electrical circuit breakers positioned adjacent one another and mounted to said housing, each said circuit breaker having a spring loaded movable electrode and an adjacent, fixed, electrode, each said movable spring loaded electrode moving along a path into and out of electrical contact with its adjacent fixed electrode in response to swinging of a pivotally mounted breaker handle along an arc between on and off positions, respectively, each said breaker handle and its said movable electrode mechanically interconnected such that the breaker handle must be swung through a larger section of said arc to move said movable electrode out of electrical contact with said adjacent fixed electrode than to move said movable electrode into electrical contact with said fixed electrode, one said circuit breaker having terminals for electrical connection between load and standard power source, and the other said breaker having terminals for connection between load and emergency power source; an interlocking device within said housing mechanically interconnected with each said circuit breaker, said device mechanically preventing said movable electrode of an open breaker from moving into contacting relationship with its said adjacent fixed electrode while the remaining said breaker has its said movable electrode in electrical contact with its said adjacent fixed electrode, and permitting said fixed and movable electrodes of said open breaker to achieve electrical contact if said electrodes of said remaining breaker are not in electrical contact; and actuation means for manually, simultaneously swinging said breaker handles along their arcs in equal increments by means of downwardly directed movement of an operator to cause said breaker handle of said open breaker to reach its on position before said handle of the closed breaker reaches its off position so said movable electrode of said open breaker becomes spring loaded so as to move into electrical contact with its said adjacent fixed electrode but is prevented from so moving by said interlocking device until said breaker handle of said closed breaker reaches its off position where its said movable electrode opens, causing said interlocking device to pErmit closing of said spring loaded movable electrode to achieve electrical contact between said fixed and movable electrode of the open breaker without danger of both said circuit breakers being simultaneously connected to the load. 